6 eggs, beaten
2 teaspoons grated lime zest
3 (14 ounce) cans sweetened condensed milk
3/4 cup canned evaporated milk
1 1/2 cups rum
1 tablespoon aromatic bitters
1 pinch freshly grated nutmeg
In a large bowl, beat eggs and lime zest using an electric mixer until light and fluffy. Gradually pour in the condensed milk while continuing to mix, and then pour in the evaporated milk.
Stir in the rum and bitters, and sprinkle with nutmeg. Transfer to a bottle and chill for at least 1 hour before serving. Serve over crushed ice.